Thickener mixtures, process for the manufacturing of transfer printing paper sheets using these mixtures, and paper sheets so obtained

ABSTRACT

The viscosity of aqueous printing inks for gravure printing is adjusted by means of partially organophilic gels which contain plastics mixtures of at least one polymer swelling in water and at least one polymer not swelling in water or to an insignificant extent only, in a solvent mixture of at least two hydrophilic organic hydroxy compounds and one hydrophobic organic hydroxy compound. The printing inks prepared with the aid of the thickener mixtures of the invention contain up to 90% of water, and can be handled as textile printing pastes. Gravure printing inks on the basis of such plastics gels containing disperse dyestuffs are suitable for the manufacture of transfer printing paper sheets. Since the thickening system adjusting the viscosity contains aqueous alcohols, if any, and no solvents as usual in transfer printing inks, no special measures have to be taken with respect to flammability and explosion risks.

This is a division of application Ser. No. 523,893, filed Aug. 15, 1983and now U.S. Pat. No. 4,454,279 which is a continuation of Ser. No.378,413, filed May 14, 1982, now abandoned.

The invention provides thickener mixtures for aqueous gravure printinginks, a process for the manufacture of transfer printing paper sheets bygravure printing with aqueous printing inks containing such thickeners,and transfer printing paper sheets so obtained.

The thickener mixtures of the invention comprise an amount of

(a) a polymer which practically does not swell in water but swells in anorganic solvent which may be diluted with up to 50 weight % of water,and

(b) a polymer which swells in water.

These two polymers in the form of their aqueous-organic gels allow toadjust the viscosity of aqueous gravure printing inks. In addition totheir thickening action, they have dispersing, film-forming andmigration-inhibiting properties.

These aqueous-organic gels are expediently prepared from concentrateswhich in addition to the two polymers contain as further components

(c) a water-soluble, low molecular weight polyhydroxy compound solid atroom temperature, and

(d) an organic solvent water-immiscible at room temperature butcompletely miscible with organic, completely water-miscible solvents.

These concentrates are then combined with a completely water-misciblesolvent liquid at room temperature, and with water. A preferredembodiment of the invention provides therefore a concentrate containingas further component (e) the completely water-miscible organic solventliquid at room temperature in addition to the two polymers (a) and (b),the solid polyhydroxy compound (c) and the water-immiscible solvent (d).

The concentrates may contain furthermore auxiliaries such assurface-active substances, for example emulsifiers, defoamers and sodiumsulfite.

Suitable polymers (a) which practically do not swell in water are thecopolymers of vinyl acetate and an unsaturated low molecular weightcarboxylic acid such as acrylic, crotonic or maleic acid, as describedin German Pat. No. 803,956 and British Pat. No. 733,507.

Suitable polymers (b) swelling in water are polyacrylic acids describedin U.S. Pat. No. 3,066,118 or German Offenlegungsschrift No. 1,595,727,or copolymers of ethylene and maleic anhydride disclosed in GermanOffenlegungsschrift No. 2,534,792.

The polymers (a) and (b) may be used also in the form of their salts,especially their ammonium or amine salts. The formation of such salts,if desired, may also be delivered subsequently in the thickener mixtureor a corresponding concentrate.

The water-soluble, low molecular weight polyhydroxy compound (c) solidat room temperature is preferably a compound of the formula

    C.sub.n H.sub.2n+2-m (OH).sub.m

in which n is an integer of from 4 to 6 and m is an integer of from 1 to6, with the proviso that m is smaller than or identical to n. Thesecompounds have advantageously a melting point of more than 50° C.Especially suitable are 1,1,1-trimethylolpropane, pentaerythritol orsugar alcohols such as sorbitol or mannitol.

Preferred organic solvents (d) water-immiscible at room temperature,completely miscible however with organic, completely water-misciblesolvents are compounds of the formula ##STR1## in which a is an integerof from 2 to 6, b is an integer of from 1 to 6, and x is a number offrom 8 to 60, with the proviso that b is smaller than or identical to a,especially oxypropylates of n-butanol, n-propanol or isopropanol.

The completely water-miscible organic solvents (e) liquid at roomtemperature are preferably compounds of the formula

    C.sub.y H.sub.2y+2-z (OH).sub.z

in wich y and z each are an integer of from 1 to 6 with the proviso thatz is smaller than or identical to y, especially compounds having aboiling point of below 90° C. Preferred are n-propanol, isopropanol,especially methanol and ethanol.

From the above components or their combinations the aqueous printinginks comprising tha background of this invention can be preparedaccording to various methods. One of these methods for example is basedon operating with separate thickener pastes: A thickener paste A isprepared from the polymer (a), the water-miscible solvent (e) and water,furthermore a thickener paste B is prepared from the water-immisciblesolvent (d), the polymer (b) swelling in water, and a water-misciblesolvent (e); these two thickener pastes A and B are mixed with additionof the solid polyhydroxy compound (c), and diluted with water whilestirring. The above or other usual auxiliaries can be added to thickenerpaste A as well as to paste B, or when stirring the two thickener pasteswith the solid polyhydroxy compound (c).

Alternatively, combinations of the thickener pastes A and B and thesolid polyhydroxy compound (c), optionally with addition of auxiliaries,can be blended to give a thickener concentrate.

In all cases, these thickener concentrates can be processed in simplemanner with the dyestuff in a normal commercial form, and with water togive a ready-in-use printing ink.

Expediently, the ready-to-use printing inks contain the followingamounts of components, per 1,000 g:

(a) 10 to 100 g, especially 10 to 50 g,

(b) 0.5 to 10 g, especially 1 to 5 g,

(c) 3 to 60 g, especially 3 to 30 g,

(d) 2 to 50 g, especially 3 to 30 g and

(e) 5 to 150 g, especially 5 to 80 g.

Relative to 1,000 g of printing ink, it is of advantage further to addthe following components:

0.05 to 0.3 g of emulsifier,

0.1 to 1 g of defoamer, and

0.1 to 0.5 g of sodium sulfite.

As emulsifiers, nonionic compounds having a HLB value (hydrophiliclipophilic balance) of from 2 to 20; as defoamers, water-solubleproducts are preferred. The sodium sulfite is practically added incrystallized form.

When using the polymers (a) and/or (b) in the form of the free acids, asuitable base is practically added to the batch, preferably about 5 to25 g of an aqueous 25% ammonia solution, relative to 1,000 g of printingink.

As far as the thickener mixtures consist of the polymers (a) and (b), orof the components (a), (b), (c) and (d), said thickener mixtures do notcontain volatile flammable solvents. Since the liquid solvent (e) isrequired in an amount only which causes the polymer (a) to swell, thethickener mixtures containing compound (e), and especially the printinginks prepared on their basis contain extremely small amounts of volatileflammable solvents only. Therefore, the safety precautions required inthe case of usual gravure printing inks on the basis of solvents can berenounced. With the use of the thickener mixtures of the invention andthe aqueous printing inks prepared therefrom, however, transfer printingpaper sheets are obtained in gravure printing allowing, surprisingly, toachieve textile prints on heat transfer printing utilizing these sheets,which are identical with respect to the quality attained in gravureprinting with corresponding solvent-containing inks. In contrast toknown aqueous printing inks, the cups of the gravure screen arecompletely emptied in the case of the printing inks according to theinvention, that is, no "missing dots" occur, which otherwise ensuresprints of even pattern.

It is especially advantageous that any paper can be printed with theprinting inks obtained with the use of the thickeners of the invention,that is, a specially pretreated paper is not required. It has alreadybeen mentioned that the disperse dyestuffs can be used in theircommercial form, so that special formulations are not required. It isfurthermore not required that the printed transfer paper sheets becoated with a protective layer.

Printing with the printing inks containing the thickeners of theinvention is carried out wet-in-dry, that is, intermediate dryingfollows the print of each color.

The invention provides therefore also a process for the manufacture ofheat transfer printing paper sheets according to the gravure printingmethod by printing of paper with aqueous printing inks containingtransferrable disperse dyestuffs, wherein the printing inks contain athickener of the invention, and an intermediate drying step follows theprint of each color. Thus, clearly outlined prints are obtained whichare of identical quality as compared to those obtained with usualgravure printing inks on the basis of solvents. The process of theinvention can be carried out according to the trichromatic system. Sincethe printing inks contain only minimum amounts of flammable solvents,the concentration thereof in the exhaust air is at such a low level thatno special measures have to be taken with respect to flammability orexplosion risks.

The transfer printing paper sheets so obtained are distinguished by aneven pattern with sharp outlines and an excellent repeat. The papersheets have a perfect storage stability and yield outstanding textileprints in heat transfer printing.

Subject of the invention are therefore also transfer printing papersheets printed according to the gravure printing process with an aqueousprinting ink containing a thickener of the invention.

The heat transfer printing process is generally known and described indetail in French Pat. Nos. 1,223,330, 1,334,829 and 1,585,119. In thisprocess, the printed transfer printing paper sheets are closelycontacted with the textile material to be printed, and the dyestuff istransferred subsequently from the carrier to the substrate and fixedthere under the action of heat and optionally elevated or reducedpressure.

The following Examples illustrate the invention; percentages being byweight unless otherwise stated.

EXAMPLE 1

Preparation of the printing inks from separate thickener pastes:

As thickener paste A, a 50% solution of a copolymer from vinyl acetateand crotonic acid, which does not swell in water, is used, prepared bydissolving

    ______________________________________                                        500 g     of the copolymer in                                                 240 g     of methanol,                                                        203 g     of water,                                                           50 g      of 25% aqueous ammonia solution, and                                7 g       of crystalline sodium sulfite                                       1,000 g                                                                       ______________________________________                                    

while stirring. The solution has a viscosity of 1.5 to 3.5 Pas.

Thickening paste B is obtained by mixing while stirring

    ______________________________________                                        641 g   of the reaction product of n-butanol with                                     17 mols of propylene oxide,                                           246 g   of the ammonium salt of a polyacrylic acid,                                   swelling in water (according to German Aus-                                   legeschrift No. 1,103,585, molecular weight                                   500,000),                                                             95 g    of ethanol, and                                                       18 g    of the reaction product of oleyl alcohol                                      with 15 mols of ethylene oxide, as emulsifier                         1,000 g                                                                       ______________________________________                                    

From these thickening pastes, the ready-to-use thickener is obtained asfollows:

    ______________________________________                                        250 g     of the thickening paste A,                                          30 g      of the thickening paste B,                                          3 g       of a water-soluble defoamer, and                                    17 g      of 1,1,1-trimethylolpropane are diluted                                       while stirring with                                                 700 g     of water                                                            1,000 g                                                                       ______________________________________                                    

From 20 to 200 g of dyestuff are intensely mixed with 250 to 300 g ofthis aqueous thickener, and diluted with water to yield 1,000 g of aprinting ink.

EXAMPLE 2

Preparation of the printing inks using one single thickener concentrate:

By mixing while stirring of

    ______________________________________                                        250 g    of the thickening paste A,                                           30 g     of the thickening paste B,                                           3 g      of a water-soluble defoamer, and                                     7 g      of 1,1,1-trimethylolpropane,                                         290 g    of ready-to-use thickener concentrate are                                     obtained.                                                            ______________________________________                                    

By mixing from 71 to 85 g of this thickener concentrate with 20 to 200 gof dyestuff and adding water to 1,000 g, a ready-to-use printing ink isprepared.

EXAMPLE 3

Trichromatic paper printing:

On a gravure printing machine (system CERUTTI-ROTOPRESS), a paper web isprinted with the following printing inks obtained according to Example1:

    ______________________________________                                                  Dyestuff according to Example set                                             forth below of European Patent                                      Dyestuff  Application No. 28,342                                                                             grams                                          ______________________________________                                        Yellow    19                    80                                            Red        3                   200                                            Blue      14                   200                                            Black     *                    400                                            ______________________________________                                        *Mixture of about                                                                        80% of blue                                                                   13% of yellow and   as indicated                                               7% of red                                                     

After the print of each color, the printed paper is subjected to anintermediate drying in a hot air drying loft.

The transfer printing paper sheet so obtained does not mark off even onprolonged storage, and yields excellent prints on polyester textilematerials in heat transfer printing.

What is claimed is:
 1. A method for making a heat transfer printingpaper sheet which comprises gravure printing a paper sheet with anaqueous printing ink comprising a heat sublimable disperse dyestuff anda thickener mixture comprising:(a) a copolymer of vinyl acetate and anunsaturated low molecular weight carboxylic acid selected from the groupconsisting of at least one of acrylic, crotonic, and maleic acid, (b) acopolymer of maleic anhydride and ethylene, or a water swellablepolyacrylic acid, (c) a water-soluble, polyhydroxy compound, solid atroom temperature, of the formula

    C.sub.n H.sub.2n+2-m (OH).sub.m

in which n is an integer of from 4 to 6 and m is an integer of from 2 to6, with the proviso that m is smaller than or identical to n, (d) anorganic solvent, water-immiscible at room temperature and completelymiscible with organic, water miscible solvents of the formula ##STR2##in which a is an integer of from 2 to 6, b is an integer of from 1 to 6,and x is a number of from 8 to 60, with the proviso that b is smallerthan or identical to a, and (e) a water-miscible organic solvent of theformula

    C.sub.y H.sub.2y+2-z (OH).sub.z

in which y and z each are an integer of from 1 to 6 with the provisothat z is smaller than or identical to y.
 2. A method as in claim 1wherein said thickener mixture comprises 10 to 100 parts by weight of(a), 0.5 to 10 parts by weight of (b), 3 to 60 parts by weight of (c),and 2 to 50 parts by weight of (d).
 3. A method as in claim 2 whereinsaid thickener mixture further comprises 0.5 to 0.3 part by weight of anemulsifier, 0.1 to 1 part by weight of a defoamer, and 0.1 to 0.5 partby weight of sodium sulfite.
 4. A heat transfer printing paper sheetmade by the method of claim 1.